This training program is designed to prepare pediatricians of any clinical subspecialty for independent, research-oriented careers in academic medicine. Its specific goal is to provide young pediatric investigators with the powerful research tools of molecular and cellular biology that will allow them to explore, in depth, basic questions related to children's health. The program faculty are selected on the basis of their demonstrated excellence in training young investigators, the strength of their research programs, and their expertise in one of three areas of pediatric research -- host defenses, developmental biology, and abnormal cellular growth. The trainees supported by this program will be selected from a pool of individuals who have already completed the clinical component of fellowship training (one year) in one of the subspecialty areas of pediatrics. The criteria for choosing these trainees will include their potential to be successful investigators, their previous academic records, and their commitment to developing independent, academically-oriented research careers. Each year the program will support five trainees; three to four will be supported in the first year of the research component of their fellowship training, and one to two in the second year. A curriculum is provided for the trainees that take advantage of the rich educational and research opportunities available at the University of Michigan Medical Center (UMMC). Trainees without a strong background in cellular and molecular biology will enroll in the intensive three month post-doctorate course in cellular and molecular biology offered by UMMC. The Department sponsors research seminars, with additional sessions to develop academic skills. The majority of the trainees' time will be spent working on individual research projects in the laboratories of their research mentors. In addition, they will participate in project-appropriate research seminars, lectures, and specialized workshops offered by the many basic and clinical sciences units of UMMC, and will have access to the excellent UMMC core laboratories. As part of their research experience, they will apply for individual awards to support completion of their research training. Progress of the trainees will be monitored by the Program Committee composed of pediatric faculty, as well as by the Advisory Committee composed of UMMC faculty outside the Department of Pediatrics. Upon completion of their post-doctoral training, trainees will be board eligible in a pediatric clinical subspecialty, and will be well-prepared for successful careers as independent, research-oriented academic pediatricians.